[Dwarf-Discuss] DWARF piece questions
Andreas Arnez
arnez@linux.vnet.ibm.com
Fri Dec 9 19:11:18 GMT 2016
Although I've already created public comments for (most of) this,
Michael Eager suggested that I post my questions regarding DWARF pieces
on this list (again).
All of these questions are related to the definition of DW_OP_piece and
DW_OP_bit_piece:
* Is "DW_OP_piece(n)" equivalent to "DW_OP_bit_piece(8*n, 0)"?
* What is the correct placement rule for register pieces? ABI-defined
or lsb0-ordered? If lsb0-ordered, how exactly is that order defined
for non-integer registers?
* Shall DW_OP_bit_piece ignore the offset for stack- and implicit
values?
* What is the "least significant bit" of an implicit value? And is it
intentional that the placement rule differs between implicit- and
memory values?
* Some DWARF producers describe a register pair just with a single
DW_OP_reg<n>. Can a register piece reach into the next register like
that as well?
* Is "DW_OP_reg*" followed by "DW_OP_piece(size of object type)" always
equivalent to omitting the piece operation?
--
Andreas
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